Unitary respirator with molded thermoset elastomeric elements

ABSTRACT

A respiratory protection composite facepiece is disclosed and includes a polymeric rigid facepiece body portion having a first surface and a second surface and a silicone sealing facepiece element chemically bonded at least one of the first surface or the second surface. The first and second surfaces can be opposing major surfaces. A second silicone element is chemically bonded to at least one of the first surface or the second surface. Methods of making the same are also disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. application Ser. No. 16/051,850, filedAug. 1, 2018, now allowed, which is a continuation of U.S. applicationSer. No. 14/573,301, filed Dec. 17, 2014, issued as U.S. Pat. No.10,065,056, which is a continuation of U.S. application Ser. No.12/670,556, filed Jan. 25, 2010, abandoned, which is a national stagefiling under 35 U.S.C. 371 of PCT/US08/070043, filed Jul. 15, 2008,which claims priority to U.S. Provisional Application No. 60/999,743,filed Aug. 31, 2007, the disclosure of which is incorporated byreference in its/their entirety herein.

FIELD

The present disclosure relates to a unitary respirator with moldedthermoset elastomeric elements and particularly to a respiratorfacepiece with a thermoset elastomeric face seal and another thermosetelastomeric element.

BACKGROUND

Half-mask respirators provide respiratory protection from airbornesubstances with filtering processes and/or otherwise facilitating accessto clean air. One characteristic of these devices is the seal that isformed between the user and other functional components of therespirator. Respirators often utilize an elastomeric material to formthe seal which is often referred to as the “faceseal.”

One design consideration with these respirators is the air-tightfastening of the elastomeric faceseal with the solid structuralcomponents of the respirator. This air-tight seal often requires amechanical seal that adds complexity and cost to the respirator design.Another design consideration is the formation and attachment of otherelastomeric elements of the respirator. These other elastomeric elementsalso add complexity and cost to the respirator design.

BRIEF SUMMARY

The present disclosure relates to a unitary respirator with moldedthermoset elastomeric elements and particularly to a respiratorfacepiece with a thermoset elastomeric face seal and another thermosetelastomeric element. This disclosure further relates to a respiratorfacepiece having a polymeric rigid facepiece body portion and a siliconesealing facepiece element and a second silicone element that ischemically bonded to at least one major surface of the polymeric rigidfacepiece body portion. In many embodiments, the silicone sealingfacepiece element and a second silicone element is chemically bonded toat least two major surfaces of the polymeric rigid facepiece bodyportion. In some embodiments, the silicone sealing facepiece element andthe second silicone element penetrates through at least one aperture inthe polymeric rigid facepiece body portion.

In a first embodiment, a respiratory protection composite facepieceincludes a polymeric rigid facepiece body portion having a first surfaceand a second surface and a silicone sealing facepiece element chemicallybonded to at least one of the first surface or the second surface. Thefirst and second surfaces can be opposing major surfaces. A secondsilicone element is chemically bonded to at least one of the firstsurface or the second surface. In some embodiments, the silicone sealingfacepiece element and/or second silicone element may be chemicallybonded to at least two opposing major surfaces of the polymeric rigidfacepiece body portion. The silicone sealing facepiece element and/orsecond silicone element may in some cases also interpenetrate aperturesthat extend through the polymeric rigid facepiece body portion. Thesecond silicone element may form a diaphragm for the inhalation valve,the exhalation valve, or speaking diaphragm, or form a sealing gasketabout an inhalation port, or form at least a portion of headstraps.

In another embodiment, a respiratory protection composite facepieceincludes a polymeric rigid facepiece body portion having a first surfaceand a second surface and an inhalation port. A silicone sealingfacepiece element is chemically bonded to at least one of the firstsurface or the second surface and forming a gasket about the inhalationport. The first and second surfaces can be opposing major surfaces. Thegasket is chemically bonded to at least one of the first surface or thesecond surface. In some embodiments, the silicone sealing facepieceelement and/or gasket may be chemically bonded to at least two opposingmajor surfaces of the polymeric rigid facepiece body portion. Thesilicone sealing facepiece element and/or gasket may in some cases alsointerpenetrate apertures that extend through the polymeric rigidfacepiece body portion.

In a further embodiment, a method of forming a respiratory protectioncomposite facepiece includes overmolding liquid silicone onto apolymeric rigid facepiece body potion having a first surface and asecond surface, where the liquid silicone is in contact with at leastone of the first surface or the second surface, and solidifying theliquid silicone to form a silicone sealing facepiece element thatchemically bonds to one of the first surface or the second surface. Asecond silicone element is chemically bonded to at least one of thefirst surface or the second surface, forming a respiratory protectioncomposite facepiece. The second silicone element may form a diaphragmfor the inhalation valve, the exhalation valve, or speaking diaphragm,or form a sealing gasket about an inhalation port, or form at least aportion of headstraps

In a still further embodiment, a method of forming a respiratoryprotection composite facepiece includes overmolding liquid silicone ontoa polymeric rigid facepiece body portion having a first surface and asecond surface, where the liquid silicone is in contact with at leastone of the first surface or the second surface, and solidifying theliquid silicone to form a silicone sealing facepiece element thatchemically bonds to one of the first surface or the second surface, andforming a gasket about the inhalation port.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be more completely understood in consideration of thefollowing detailed description of various embodiments of the inventionin connection with the accompanying drawings, in which:

FIG. 1 is a perspective view of an illustrative respiratory protectionmask;

FIG. 2 and FIG. 3 are schematic cross-section views of an illustrativeinhalation or exhalation diaphragm valve;

FIG. 4 is a schematic cross-section view of an illustrative speakingdiaphragm;

FIG. 5 is a perspective view of an illustrative rigid facepiece body fora respirator protection mask;

FIG. 6 is a perspective front view of the rigid facepiece body shown inFIG. 5 illustrating a silicone sealing facepiece element overmolded ontohalf of the rigid facepiece body;

FIG. 7 is a perspective rear view of the rigid facepiece body shown inFIG. 5 illustrating a silicone sealing facepiece element overmolded ontohalf of the rigid facepiece body;

FIG. 8 is a schematic cross-sectional view of portion of a respiratoryprotection composite facepiece illustrating a mechanical interlockcreated when the liquid silicone interpenetrates an aperture through therigid facepiece body; and

FIG. 9 is a perspective partial exploded view of an illustrativerespiratory protection mask.

The figures are not necessarily to scale. Like numbers used in thefigures refer to like components. However, it will be understood thatthe use of a number to refer to a component in a given figure is notintended to limit the component in another figure labeled with the samenumber.

DETAILED DESCRIPTION

In the following description, reference is made to the accompanyingdrawings that form a part hereof, and in which are shown by way ofillustration several specific embodiments. It is to be understood thatother embodiments are contemplated and may be made without departingfrom the scope or spirit of the present invention. The followingdetailed description, therefore, is not to be taken in a limiting sense.

All scientific and technical terms used herein have meanings commonlyused in the art unless otherwise specified. The definitions providedherein are to facilitate understanding of certain terms used frequentlyherein and are not meant to limit the scope of the present disclosure.

Unless otherwise indicated, all numbers expressing feature sizes,amounts, and physical properties used in the specification and claimsare to be understood as being modified in all instances by the term“about.” Accordingly, unless indicated to the contrary, the numericalparameters set forth in the foregoing specification and attached claimsare approximations that can vary depending upon the desired propertiessought to be obtained by those skilled in the art utilizing theteachings disclosed herein.

The recitation of numerical ranges by endpoints includes all numberssubsumed within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3,3.80, 4, and 5) and any range within that range.

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” encompass embodiments having pluralreferents, unless the content clearly dictates otherwise. As used inthis specification and the appended claims, the term “or” is generallyemployed in its sense including “and/or” unless the content clearlydictates otherwise.

The term “respirator” means a personal respiratory protection devicethat is worn by a person to filter air before the air enters theperson's respiratory system. This term includes full face respirators,half mask respirators, supplied air hoods, powered air purifyingrespirators, and self contained breathing apparatus.

The present disclosure relates to a unitary respirator with moldedthermoset elastomeric elements and particularly to a respiratorfacepiece with a thermoset elastomeric face seal and another thermosetelastomeric element. The present disclosure also relates to a respiratorfacepiece having an inhalation port and a thermoset elastomeric faceseal that also surrounds the inhalation port forming an inhalation portgasket. This disclosure further relates to a respirator facepiece havinga polymeric rigid facepiece body portion and a silicone sealingfacepiece element and a second silicone element that is chemicallybonded to one or two major surfaces of the polymeric rigid facepiecebody portion. In some embodiments, the silicone sealing facepieceelement and the second silicone element also penetrates through thepolymeric rigid facepiece body portion. This respirator facepiece can beformed by molding a thermoset silicone sealing facepiece element and asecond silicone element onto the polymeric thermoplastic rigid facepiecebody portion sequentially or at the same time. These respiratorfacepieces have a robust bond between the silicone elements and therigid facepiece body portion. While the present invention is not solimited, an appreciation of various aspects of the invention will begained through a discussion of the examples provided below.

The unitary respirator having an overmolded thermoset elastomeric sealand another overmolded element provides a face sealing element and otherelastomeric element that is integrally or chemically bonded with thepolymeric rigid facepiece body portion. This construction has been foundto enhance the durability of the elastomeric elements and prevent debrisfrom being interposed between the polymeric rigid facepiece body portionand the thermoset elastomeric elements. This integral construction alsoreduces the number of assembly parts and part size variability. Theovermolded thermoset elastomeric materials described herein also do notrequire that the polymeric rigid facepiece body portion be primed inorder for the thermoset elastomeric elements to be chemically attachedor bonded to the polymeric rigid facepiece body portion.

FIG. 1 is a perspective view of an illustrative respiratory protectionmask 10. The respiratory protection mask 10 includes a respiratoryprotection composite facepiece 11 attached to number of respiratoryprotection elements including, for example, one or more inhalationvalves with an optional chemical or particulate filtration cartridge 28connected to one or more of the inhalation valves, one or moreexhalation valves 32, one or more speaking diaphragms and/or one or moreheadstraps or straps 34 configured to secure the respiratory protectioncomposite facepiece 11 to a user's head.

The respiratory protection composite facepiece 11 includes a siliconesealing facepiece element 12 overmolded onto a polymeric rigid facepiecebody 20 (as described in more detail below). The chemical or particulatefiltration cartridge 28 to can be either fixedly attached or removablyattached to the one or more of the inhalation valves. In someembodiments, the silicone sealing facepiece element 12 also forms a sealor gasket (as described in more detail below) between the chemical orparticulate filtration cartridge 28 and the polymeric rigid facepiecebody 20 or inhalation valve (as described in more detail below). Thechemical or particulate filtration cartridge 28 can have any usefulshape, other than the shape illustrated in FIG. 1 .

While FIG. 1 illustrates a respiratory protection mask 10 having twocheek inhalation valves attached to a chemical or particulate filtrationcartridge 28 and one nose exhalation valve 32, any useful respiratoryprotection configuration is possible. For example, the respiratoryprotection mask 10 can have a single inhalation valve attached to achemical or particulate filtration cartridge 28 or clean air supply andone or two exhalation valves or one or more speaking diaphragms, asdesired.

FIG. 2 and FIG. 3 are schematic cross-section views of an illustrativeinhalation or exhalation valve. FIG. 4 is a schematic cross-section viewof an illustrative speaking diaphragm. These inhalation or exhalationvalves or speaking diaphragm are located within or adjacent to theplurality of openings of the rigid facepiece body 20, described below.

FIG. 2 illustrates a partial schematic diagram of a diaphragm valvedisposed between an exterior area 1 or 2 and an interior area 2 or 1 ofthe illustrative respiratory protection mask 10. The valve 25 is aninhalation valve when the diaphragm 26 is disposed between the rigidfacepiece body 20 and the user's face or the interior area 2 of theillustrative respiratory protection mask 10. The valve 25 is anexhalation valve when the diaphragm 26 is disposed between the rigidfacepiece body 20 and the exterior area 1 of the illustrativerespiratory protection mask 10. FIG. 3 illustrates the valve allowingeither inhalation air 5 or exhalation air 5 to pass between thediaphragm 26 and the valve body or rigid facepiece body 20. Theexemplary diaphragm 26 is attached to a valve support element 19 thatanchors the diaphragm 26 to the valve body or rigid facepiece body 20.One or more struts 17 (see FIG. 5 ) can connect the support element 19that anchors the diaphragm to the valve body or rigid facepiece body 20.

FIG. 4 illustrates a partial schematic diagram of a speaking diaphragm.The illustrative speaking diaphragm includes a diaphragm 27 fixed to therigid facepiece body 20. While the diaphragm 27 is illustrated beingsandwiched between two rigid facepiece body 20 body portions, thediaphragm 27 may be simply chemically bonded to one or both of the firstsurface and a second surface (described below) and may penetrate throughat least one aperture in the polymeric rigid facepiece body portion(described generally below). The diaphragm 27 is disposed between theexterior area 1 or 2 and an interior area 2 or 1 of the illustrativerespiratory protection mask 10. The speaking diaphragm 27 assists in thetransmission of speech from the respiratory protection mask 10 user.

FIG. 5 is a perspective front view of an illustrative rigid facepiecebody 20 for a respirator protection mask 10. The rigid facepiece body 20includes a first surface 21 and a second surface 22. In the illustratedembodiment, the first surface 21 and a second surface 22 are opposingmajor surfaces of the rigid facepiece body 20, separated by a bodythickness T. In the illustrated embodiment, the first surface 21 is anouter surface (directed toward the environment) and the second surface22 is an inner surface (directed toward a user's face). The illustratedrigid facepiece body 20 includes a plurality of openings or ports suchas, for example, a nose opening 16 and two cheek openings 18. At leastone inhalation valve including a diaphragm (not shown) and oneexhalation valve including a diaphragm (not shown) are disposed withinthe plurality of ports or openings and forms the illustrated rigidfacepiece body 20. In some embodiments, a speaking diaphragm is disposedwithin one or more of the plurality of ports or openings.

In many embodiments, one or more apertures 23 extend through the bodythickness T. During the overmolding manufacture of the respiratoryprotection composite facepiece 11 liquid silicone (that forms thesilicone sealing facepiece element 12) flows through the one or moreapertures 23 and forms a mechanical interlock between the siliconesealing facepiece element 12 and the rigid facepiece body 20. In someembodiments, the inhalation valve includes a chemical or particulatefiltration cartridge attachment element 29. In many embodiments, theattachment element 29 is a bayonet attachment element that mates with acomplementary element on the chemical or particulate filtrationcartridge attachment element 29. A bayonet attachment system isconfigured for attaching two portions together, where the two portionsinclude elements other than mainly threads such that the two portionsare attached by inserting one portion at least partially within theother portion and rotating one portion relative to the other portion sothat the two portions can be joined without multiple turns.

FIG. 6 is a perspective front view of the rigid facepiece body 20 shownin FIG. 5 with a silicone sealing facepiece element 12 overmolded ontohalf of the rigid facepiece body 20. FIG. 7 is a perspective rear viewof the rigid facepiece body shown in FIG. 5 with a silicone sealingfacepiece element overmolded onto half of the rigid facepiece body. Itis understood that the exemplary respiratory protection compositefacepiece 11 includes the silicone sealing facepiece element 12overmolded onto both halves of the rigid facepiece body 20, but is shownas a cross-section of the silicone sealing facepiece element 12 to moreeasily illustrate the contour of the silicone sealing facepiece element12.

The rigid facepiece body 20 is described above. The silicone sealingfacepiece element 12 is chemically bonded to at least one of a firstsurface and a second surface of the rigid facepiece body 20, such thefirst surface 21 and/or the second surface 22. In many embodiments, thesilicone sealing facepiece element 12 is chemically bonded to at leastone of the first surface 21 and the second surface 22, where the firstsurface 21 and a second surface 22 are major surfaces of the rigidfacepiece body 20, separated by a body thickness T, as described above.

A second silicone element is chemically bonded to at least the firstsurface 21 and/or the second surface 22. The second silicone element canbe any silicone element or component useful in a respiratory protectionmask. The second silicone element can be, for example, a diaphragm forthe inhalation valve, exhalation valve, or speaking diaphragm, or form asealing gasket about an inhalation port, or form at least a portion ofheadstraps, for example. The second silicone element can be formed(e.g., overmolded) at the same time or sequentially as the siliconesealing facepiece element 12 is formed (e.g., overmolded).

During the overmolding manufacture of the respiratory protectioncomposite facepiece 11 liquid silicone (that forms the silicone sealingfacepiece element 12 or second silicone element) flows through the oneor more apertures 23 and forms a mechanical interlock between thesilicone sealing facepiece element 12 and the rigid facepiece body 20once the liquid silicone is cured to its solid state. During thisovermolding process, or in a sequential overmolding process, the secondsilicone element is formed by liquid silicone that flows onto at leastthe first surface 21 and/or the second surface 22 and optionally throughone or more apertures in the mask body and forms a mechanical interlockbetween the mask body and the second silicone element, once the liquidsilicone is cured to its solid state.

FIG. 8 illustrates a schematic cross-sectional view of portion of arespiratory protection composite facepiece 11 illustrating a mechanicalinterlock created when the liquid silicone interpenetrates an aperture23 through the rigid facepiece body 20. The silicone sealing facepieceelement 12 and/or second silicone element can be disposed on andchemically bonded to the first surface 21 and/or the second surface 22,where the first surface 21 and a second surface 22 are major surfaces ofthe rigid facepiece body 20, separated by a body thickness T, asdescribed above.

Referring back to FIG. 6 and FIG. 7 , the silicone sealing facepieceelement 12 is configured to form an air-tight seal between a user's heador face and the rigid facepiece body 20. The term “air-tight seal”refers to a connection of the silicone sealing facepiece element 12 tothe user's face or head that substantially prevents unfiltered orambient air from entering an interior portion of the respiratoryprotection composite facepiece 11 at the connection interface. Theillustrated silicone sealing facepiece element 12 includes an in-turnedfeathered cuff 14 that contacts a user's face.

Air-tightness is measured with a vacuum leak test. The test fixtureconsists of a sealed chamber with three ports. The volume of the chamberis approximately 750 cm³. A respirator attachment component is affixedto one of the three ports by means of its bayonet attachment element. Avacuum gauge capable of measuring the pressure differential between theinside of the chamber and the ambient air (to at least 25 cm water) isattached to a second port on the fixture. A vacuum source is attached tothe third port through a shut off valve. To conduct the test, theshut-off valve is opened and the vacuum source is turned on to evacuatethe chamber to a pressure of 25 cm water below atmospheric pressure (asindicated by the vacuum gauge). The shut-off valve is then closed andthe vacuum source is turned off. The vacuum level inside the chamber ismonitored for 60 seconds. Inward leakage of air causes the pressureinside the chamber to increase, thereby reducing the vacuum level. Forthe current invention, the pressure differential between the chamber andthe ambient air is greater than 15 cm of water after 60 seconds. Morepreferably, the pressure differential remains above 24 cm of water after60 seconds.

The respiratory protection composite facepiece 11 can be formed byovermolding a thermosetting silicone material onto a thermoplastic rigidfacepiece body 20. The thermosetting silicone material chemically bonds(i.e., adhesive bonding or covalent bonding) to the thermoplastic rigidfacepiece body 20.

The terms “chemical bonding or chemically bonded” refer to physicalprocesses responsible for the attractive interactions between atoms andmolecules and includes covalent and ionic bonds, as well as hydrogen andvan der Waal's bonds and can often depend on available functional groupson the rigid facepiece body 20 surface and their reactivity with thethermosetting silicone material. In many embodiments, the thermosettingsilicone material is selected so that pretreatment of the thermoplasticrigid facepiece body 20 is not necessary. In other words, thethermosetting silicone material is self-adhesive with the thermoplasticrigid facepiece body 20. The thermosetting silicone material is oftenheated to cure the thermosetting silicone material during theovermolding process to a temperature sufficient to cure thethermosetting silicone material but less than a glass transitiontemperature of the thermoplastic rigid facepiece body 20.

As shown in the Examples below, the level of chemical bonding can bedetermined by the average force to failure test method. In manyembodiments, the average force to failure is 25 N or greater, 50 N orgreater, or 100 N or greater, or 150 N or greater, or 200 N or greater,or 300 N or greater.

The thermoplastic rigid facepiece body 20 can be formed of any usefulthermoplastic material. In many embodiments, the thermoplastic rigidfacepiece body 20 is formed of a polyamide (e.g., nylon), apolycarbonate, polybutylene-terephthalate, polyphenyl oxide,polyphthalamide, or mixtures thereof.

Any useful thermosetting liquid silicone rubber or material can beutilized to form the silicone sealing facepiece element 12 and secondsilicone element. Liquid silicone rubber is a high purity platinum curedsilicone with low compression set, great stability and ability to resistextreme temperatures of heat and cold. Due to the thermosetting natureof the material, liquid silicone injection molding often requiresspecial treatment, such as intensive distributive mixing, whilemaintaining the material cool before it is pushed into the heated cavityand vulcanized. Silicone rubber is a family of thermoset elastomericsthat have a backbone of alternating silicone and oxygen atoms and methylor vinyl side groups. Silicone rubbers constitute about 30% of thesilicone family, making them the largest group of that family. Siliconerubbers maintain their mechanical properties over a wide range oftemperatures and the presence of methyl-groups in silicone rubbers makesthese materials hydrophobic.

Illustrative thermosetting silicone material includes self-adhesiveliquid silicone rubbers available under the trade designation: ELASTOSILLR 3070 from Wacker-Silicones, Munich, Germany; the KE2095 or KE2009series (such as, for example, KE2095-60, KE2095-50, KE2095-40) orX-34-1547A/B, X-34-1625A/B, X-34-1625A/B all from Shin-Etsu ChemicalCo., LTD., Japan. These self-adhesive liquid silicone rubbers do notrequire pretreatment of certain thermoplastic surfaces for the liquidsilicone rubbers to chemically bond to the thermoplastic surface.

FIG. 9 is a perspective partial exploded view of an illustrativerespiratory protection mask 11. The mask includes a rigid facepiece body20 is described above, a silicone sealing facepiece element 12 ischemically bonded to the rigid facepiece body 20, a nose opening 16 andtwo cheek openings 18. At least one inhalation port 18 or valveincluding a diaphragm (i.e., second silicone element) and one exhalationport 16 or valve including a diaphragm 26 (i.e., second siliconeelement) is disposed within the plurality of ports or openings. Asilicone gasket 31 (i.e., second silicone element) is disposed about thechemical or particulate filtration cartridge attachment element 29 andinhalation port 18 or valve. The silicone gasket 31 forms an air-tightseal with the chemical or particulate filtration cartridge 28 and therigid facepiece body 20.

The silicone gasket 31 and silicone exhalation diaphragm 26 (andinhalation diaphragms) can be formed simultaneous or sequentially andchemically bonded to the to the rigid facepiece body 20. In someembodiments, silicone gasket 31 and silicone exhalation diaphragm 26(and inhalation diaphragms) penetrate through the rigid facepiece body20 as illustrated in FIGS. 2, 3, and 8 .

The chemical or particulate filtration cartridge 28 to can be eitherfixedly attached or removably attached to the chemical or particulatefiltration cartridge attachment element 29. The chemical or particulatefiltration cartridge 28 can have any useful shape, other than the shapeillustrated in FIG. 9 .

EXAMPLES

Several tests were used to identify suitable combinations of siliconerubbers and thermoplastic materials. Of particular interest is thestrength of the bond between the silicone rubber and thermoplasticmaterial, which affects the durability of the air-tight seal.

The test strip is prepared by molding a rigid, flat substrate piece 51mm long, 25 mm wide, and 2 mm thick with thermoplastic material. Thesubstrate is then clamped into a second mold such that 6 mm of one endof the substrate protrudes into the cavity of the second mold. Thecavity of the second mold is 27 mm wide and 49 mm long. The depth of themold is 2 mm, expanding to 4 mm in the immediate vicinity of theprotruding substrate end, such that when silicone is injected into themold cavity it forms a layer 1 mm thick on all sides of the protrudingsubstrate end. The resulting test strip is thus 94 mm long, with a rigidthermoplastic substrate piece on one end and silicone rubber on theother end.

The strength of the bond between the substrate material and silicone ismeasured by gripping the two ends of the test strip in the jaws of amechanical tester such as an MTS Model 858 Material Test System (MTSSystems Corporation, Eden Prairie, MN), stretching it until the teststrip breaks apart, and recording the force at which failure occurs.Examples of the force to failure are shown in Table 1. Examples 1through 4 show that bond strengths greater than 300 N can be achievedwith the appropriate combination of materials. For Comparative ExamplesC1 and C2, the silicone did not bond to the thermoplastic material.

Thermoplastic Average Force Example Silicone Substrate to Failure (N) 1Shin-Etsu KE2095 60 RTP Nylon 6/6 136 2 Wacker 3070-60 RTP Nylon 6/6 3033 Dow LC-70-2004 Zytel PA 174 4 Wacker 3070-60 Zytel PA 166 C1 DowLC-70-2004 RTP Nylon 6/6 No bonding C2 Shin-Etsu KE2095 60 Zytel PA Nobonding

Dow LC-70-2004 silicone is produced by Dow Corning Corporation, MidlandMI; RTP Nylon 6/6 is a polyamide produced by RTP Company, Winona, MN;Zytel PA is a polyamide produced by E.I. du Pont de Nemours, Wilmington,DE.

Thus, embodiments of the UNITARY RESPIRATOR WITH MOLDED THERMOSETELASTOMERIC ELEMENTS are disclosed. One skilled in the art willappreciate that the present invention can be practiced with embodimentsother than those disclosed. The disclosed embodiments are presented forpurposes of illustration and not limitation, and the present inventionis limited only by the claims that follow.

What is claimed is:
 1. A method of forming a respiratory protectioncomposite facepiece comprising: overmolding liquid silicone onto apolymeric rigid facepiece body potion having a first surface and asecond surface, the liquid silicone in contact with at least one of thefirst surface or the second surface; and solidifying the liquid siliconeto form a silicone sealing facepiece element that chemically bonds toone of the first surface or the second surface, and a second siliconeelement chemically bonded to at least one of the first surface or thesecond surface, forming a respiratory protection composite facepiece. 2.A method according to claim 1, wherein the polymeric rigid facepiecebody portion further comprises an inhalation valve or an exhalationvalve and the solidifying step forms a second silicone element diaphragmfor the inhalation valve or the exhalation valve.
 3. A method accordingto claim 1, wherein the solidifying step solidifies the liquid siliconeto form a silicone sealing facepiece element that chemically bonds tothe first surface and the second surface.
 4. A method according to claim1, wherein the polymeric rigid facepiece body portion comprises aplurality of apertures extending through the polymeric rigid facepiecebody portion and the overmolding step interpenetrates liquid siliconeinto at least a portion of the apertures to form the silicone sealingfacepiece element.
 5. A method according to claim 1, wherein polymericrigid facepiece body portion comprises an inhalation valve and thesolidifying step second silicone element forms a gasket surrounding theinhalation valve.
 6. A method according to claim 1, wherein thesolidifying step second silicone element forms at least a portion of oneor more straps configured to secure the respiratory protection compositefacepiece to a user's head.
 7. A method according to claim 2, furthercomprising attaching a chemical or particulate filtration cartridge tothe inhalation valve.
 8. A method of forming a respiratory protectioncomposite facepiece comprising: overmolding liquid silicone onto apolymeric rigid facepiece body portion having a first surface and asecond surface, the liquid silicone in contact with at least one of thefirst surface or the second surface; and solidifying the liquid siliconeto form a silicone sealing facepiece element that chemically bonds toone of the first surface or the second surface, and forming a gasketabout the inhalation port.
 9. A method according to claim 8, wherein thesolidifying step solidifies the liquid silicone to form a siliconesealing facepiece element that chemically bonds to the first surface andthe second surface.
 10. A method according to claim 8, wherein thepolymeric rigid facepiece body portion comprises a plurality ofapertures extending through the polymeric rigid facepiece body portionand the overmolding step interpenetrates liquid silicone into at least aportion of the apertures to form the silicone sealing facepiece element.